In accordance with a development of a liquid crystal display (LCD) technology, a requirement for elements of a liquid crystal display panel is raised gradually.
At present, in a COF type package structure, a driving chip is basically packaged with hot press by tape automated bonding (TAB). The COF type package structure is coiled for transporting. When using the COF type package structure, COF structures can be obtained by cutting a tape substrate, and are electrically connected between a circuit on a glass substrate of an LCD panel and a driving circuit board. At least one COF structure is disposed between the glass substrate and the driving circuit board. The larger a size of the LCD panel is, the more an amount of the required COF structures is.
Referring to FIG. 1, in the COF structure shown in FIG. 1, a longitudinal direction D2 of a driving chip 11 is vertical to a longitudinal direction D1 of a tape substrate 10. The tape substrate 10 has input leads 12 and output leads 13, wherein the input leads 12 are close to a printed circuit board (PCB), and the output leads 13 are close to a glass substrate for outer lead bonding (OLB). The input leads 12 and the output leads 13 are disposed at both sides of the driving chip 11 and arranged radially along the longitudinal direction D1 of the tape substrate 10.
Taking the output leads 13 for example, the output leads 13 are connected to a transparent circuit (not shown) on the glass substrate. The amount of the output leads 13 is more than the input leads 12, and the output leads 13 are arranged very closely. However, in the conventional COF, a width of the tape substrate 10 is less and limited (normally 35 or 48 mm). Thus, the width of each chip (COF) on the tape substrate 10 is also limited. Moreover, with an increase of the amount of the COFs, the leads of each COF are required to be increased. Therefore, obviously, the conventional COF can not meet a high circuit density requirement for the LCD panel of large size.
Accordingly, in the field of the LCD technology, it is a problem that the conventional COF (especially the output leads of the COF) can not meet the high circuit density requirement for the LCD panel of large size.